Adaptation of a Brush Cutter for Kenaf (Hibiscus cannabinus) Harvesting

The adaptation of some existing technologies such as sugarcane-type harvester, jute/reed-type harvesters and forage harvesters for kenaf harvesting has not been successful. These machines apart from being expensive cut kenaf stems into too short fragments. Information regarding machines for kenaf harvesting is rarely found in the literature. In this work, an existing 1.65 kW brush cutter was modified and adapted for kenaf harvesting with the view to developing a low-cost machine for kenaf harvesting. The modifications made include incorporating a suitable metal guard based on the physical properties of kenaf stem and selection of an appropriate serrated blade cutting mechanism. The machine was tested on an experimental field of 3 and 4 months old kenaf plantation, and its performance was evaluated considering the effective field capacity, theoretical field capacity, field efficiency and fuel consumption. The results showed that the field efficiency of the machine ranged from 69.15 – 81.21%. The theoretical field capacity and fuel consumption were 0.14 ha/hr, and 46.91 L/ha, respectively. Furthermore, it was found that kenaf variety had a significant effect (p<0.05) on the theoretical field capacity. The field efficiency was significantly affected (p<0.05), by the maturity of the kenaf plant and harvester blade type. However, blade type and kenaf varieties do not have a significant effect on fuel consumed by the harvester. The kenaf harvesting machine was able to harvest the two kenaf varieties considered in this study when fitted with the 3-tooth and 40-tooth brush cutter blades.  A machine of this nature is a positive development in kenaf harvesting, which hitherto has been an arduous task for kenaf farmers.